1. Field of the Invention
The present invention relates to a multi-wavelength optical transceiver module, and multiplexer/demultiplexer using a thin film filter, and more specifically, to a multi-wavelength optical transceiver module, and multiplexer/demultiplexer using a thin film filter capable of producing an optical module at low cost in large quantities by hybrid-integrating a thin film filter, an optical transmitter, an optical receiver, and an optical fiber into a PLC platform.
2. Discussion of Related Art
In general, with an expansion of an optical communication system largely used in a backbone network into a subscriber network, various types of optical modules required in arranging the subscriber network are in high demand.
Particularly, for an optical transceiver module arranged in the subscriber side, such as a bi-directional optical transceiver module or an optical triplexer transceiver module and an optical quadraplexer transmitter and receiver module, low cost and mass production are key factors to determine the competitiveness.
Therefore, an optical integrated module technology has been developed that optical devices such as a thin film filter, a laser diode (LD), and a photodiode (PD) are hybrid-integrated on a PLC platform at the same time to manufacture the optical module in high performance at low cost.
In a conventional hybrid optical integrated module technology, one method of manufacturing an optical triplexer transceiver module is to form grooves of about 30 μm at two places in a silica planar lightwave circuit (hereinafter, referred to as ‘PLC’) and insert a thin film filter to thus implement a wavelength multiplexing device that separates wavelengths of 13910/1490/1550 nm, and mount active devices such as laser diodes (LD) and photodiodes (PD) onto a silica platform through precise flip-chip bonding.
However, the prior art described above has a problem in that a loss of reflected light significantly varies according to how much the thin film filter is inserted. In other words, the grooves into which the thin film filter is inserted are difficult to be uniformly formed at the exact place in a longitudinal direction with a narrow width, and when the thin film filter is inserted into the grooves and fixed with an index-matching epoxy, a tilt occurs so that light is not exactly incident on a reflection (caused by thin film filter) optical waveguide relative to an input optical waveguide.
Therefore, it is difficult to reduce an optical loss reflected at the thin film filter to about 1 dB, which is a factor that degrades the yield upon mass production, so that it is disadvantageous in terms of the low cost.
In addition, upon mounting the active devices such as the laser diode (LD) or the photodiode (PD) in the prior art, an expensive flip chip bonding apparatus should be used to ensure alignment accuracy to be within several μm, and forming a V-groove directly in the PLC to pigtail a predetermined optical fiber is an extremely difficult process, which is not appropriate for mass production.
In addition, since a waveguide photodiode (PD) is used in the prior art, there is a difficulty in demand and supply of the photodiode (PD) having good characteristics upon commercialization. Further, since the waveguide photodiode (PD) does not have good characteristics with respect to responsivity and inter-modulation distortion (IMD) relative to the commercialized pin-PD, there is a problem in arranging a receive unit, which is burdensome while packaging.
Therefore, in order to achieve the mass production and commercialization, there is a need for a method of easily fixing the thin film filter to the PLC, easily implementing performance of an optical transceiver module with a good-characteristic and commercialized pin-PD, and aligning and pig-tailing an optical fiber in a manner not to degrade the overall manufacturing yield.